Magneto



J. B. BUSHNELL.

MAGNETO.

APPLICATlON FILED MAY 24. 1919.

Patented Jan. 11, 1921.

2 SHEETS-SHEET 5 INVENTOI? I 17 ATTORNEY J. B. BUSHNELL.

MAGNETO.

APPLICATION FILED MAY 24. 1 919.

1,365,225. A Patented Jan. 11, 1921.

2 SHEETSSHEET 2.

IN V EN TOR.

BYQ

TTORNEY f UNITED sures PATENT OFFICE.

JOHN BENJAMIN BUSHNELL, OF BERKELEY, CALIFORNIA, ASSIGNOR TO BUSHNELL MAGNE'IO CORPORATION, OF BERKELEY, CALIFORNIA.

MAGNE'IO.

1,eea,225.-

1'0 all whom it may concern:

Be it known that I, JOHN BENJAMIN BUSHNELL, a citizen of the United States, residing at Berkeley, in the county of Alameda, State of California, have invented certain new and. usefullmprovements in Magnetos; and I do declare the follo'wi to be a full, clear, and exact descriptlon of the same, reference being had to the accompanywith a simple and eflicient impulse starter,v

whereby a spark of suflicient intensity for starting internal combustion engines with out the use of storage or other batteries may be had while the engine is being turned over slowly.

As is well known, the spark produced at the timer contacts of a magneto is insufficient to explode the compressed fuel-mix ture in the cylinders of the engine when the magneto is turning at very slow speed.

I have therefore interposed a means in the armature shaft between the armature itself and the driving connection of the shaft with the crank shaft'of the engine so that when the timer is set to give a retarded sparkthis being the correct position of the same when the engine is started-the turning of the crank shaft end of the armature shaft will cause the armature end of such shaft to turn at an -accelerated speed'past the contact points in the timer box, which action will continue until the spark is advanced to running position when the normal speed of the magneto is sufiicient to produce a spark of the required intensity.

I have also so arranged the device that it may be removed if for any reason it is not desired, or is out of order, and the magneto may be used and connected to the engine in the same manner as before by merely shifting its position on the engine base.

A magneto with this attachment is particularly adapted for use on aeroplanes, where the use of self-starters is not advisable, owing to their weight, and on heavy duty stationary or boat engines which are Specification of Letters Patent. Pat t 1 1921 Application filed Kay 24, 1919. Serial No. 299,464. I

very heavily built and hence are turned over very slowly when trying to start the same.

Another object of my invention is to construct a slmple, durable and relatively inexpenslve device, and one not likely to soon get out of order or wear out.

These objects I accomplish by means of such structure and relative arrangement of parts as Wlll fully appear by a perusal of the following specification and claims.

On the drawings similar characters of reference indicate corresponding parts in the several views.

Figure 1 is a side elevation of my proved type of magneto showing my pulse starter located thereon.

Fig. 2 is a vertical section through starter.

imimthe Fig; 3 is a cross section of the same, taken relatively on a line 33 of Fig. 1.

Fig. 4 is a fragmentary top. plan view of a slotted spring casing, being also the member directly connected to the crank or cam shaft of the engine. s Fig. 5 is a cross section of the magneto taken on a line 5-5 of Fig. 1. F 6 is a perspective view of the secondary pole shoes. Referring now more particularly to the characters of reference on the drawings, the numeral 1 denotes the base of the magneto having the usual magnets 2 thereon, and a box 3 at one end containing the timer mech anism and provided with a lever arm 4 adapted for vertical movement to control the time of sparking. of the magneto relative to the cycles of turning of the crank shaft of the engine, as is common custom. As the terms retarded and advanced are now commonly usedto indicate such relative the timer mechanism is a bearing ring 6,

in which the shoes 5 turn, the other ends of the shoes being fixed to the movable member of the timing mechanism.

Secured to the end of the member 5 beyond the bearing 6 is a cam disk 7 provided with a suitable peripheral cam recess 8 therein, the lowest point A thereof being adapted to lie in a vertical line from the center of the disk when the lever 4 is moved to its full-retard position.

The armature shaft 9 of the magneto projects beyond this disk, and is tapered, keyseated and threaded in conformity with standard S. A. E. dimensions.

Keyed onto this end of the shaft 9 is the hub 10 of a disk 11, somewhat smaller in diameter than the disk 7 and being provided with a pair of diametrically opposed and outwardly projecting dogs or lugs 12, whose ends are wedge shaped longitudinally of the hub 10, as shown at 13, the outside diameter of these dogs being slightly less that the normal diameter of the cam-disk 7.

The hub 10 extends beyond the end of the shaft 9, such end containing a lock nut 14 threaded onto the end of the shaft.

T urnably mounted on the hub 10 is a hub 15 whose outer end is formed as a shaft-end 16 of the same shape and dimensions as the end of the shaft 9, so as to adapt it for connection to gear or .chain driving means.

The hub 15 has a disk or flange 17 thereon, which in turn has an annular flange 18 around its outer edge, this flange being adapted to abut against the disk 7. This flange is also provided with notches or recesses 19 in such abutting edge, these recesses being of a depth suflicient to retain the dogs 12 thereon, and having a length substantially equal to the arcuate movement of the disk 7.

A stiff spiral spring 20 is positioned in the space formed between the disk 11 and flange 17, one end being secured to the hub 10 and the other end to the flange 18.

A casing 21 envelops the members 5, 17 and intermediate parts, the hub 15 projecting therethrough. Y

On top of this casing is mounted a hollow boss 22 having a pawl 23 of rectangular cross section slidable therein, this pawl having its lower end wedge shaped, as are the dogs 12 and in the same direction. The widthof this pawl is equal to that of disks 7 and 11 combined, so that it will both ride on the disk 7 or in the cam-recess 8 thereof and will abut against the dogs 12 while in such recess.

A strong spiral spring 24 in the boss 22 rests on the dog 23, and is adjustably held .in compression thereagainst by means of a set screw 2 1 threaded into the boss 22.

The operation of I the device is as follows :-The figures on the drawings show the timer mechanism in itsfarthest advanced position, and the armature shaft 9 or the extension 16 turning clockwise.

Supposing the lever 4 to be turned to its most retarded position, the lowest point A of the recess 8 of the cam or timer disk 7 will I be on a vertical line through the center of the disk, as heretofore stated, or in other words, immediately under the pawl 23. This pawl will then rest in the recess, owing to the downward pressure of the spring 24, and hence its end will be below the level of the dogs 12 on the disk 11. The normal position of the upper one of the dogs 12 in the upper slot 19 is at the right hand end thereof (in the position shown in Figs. 3 and 1) owing to the spring 20, which has a tendency to uncoil in that direction.

Then, if the shaft 16 is turned slowly, as in cranking an engine by hand, while the the pawl 23 is in the recess 8 as stated, the dog 12 will impinge against the pawl 23, and the spring 20 will be wound up until the left hand end of the slot 19 will abut against the dog 12, at which point the turning movement of the flange 18v (inwhich is the slot 19') being continuous of course with the turning of the shaft 16, the pawl 23 is raised by the combined pressure of the member 18 and the spring '20 on the dog 12, and the dog 12, thus released, causes the wound spring 20 to act on the hub 10 (which is integral with the dogs 12 and keyed to the armature shaft 9) so as to turn the same momentarily at a great rate of speed, that is, for the length of the slot 19, thus creating a very hot spark at the contact points in the timer box, and thence at the spark plugs of the engine.

The position of the dogs 12 on the disk 11 relative to the contact points in the timer box 3 is of course such that a contact is made with the release of each dog.

The same operation takes place when the other dog is turned to abut against the pawl 23, and such actuations will continue to take place until .the .engine comes up to speed, when the centrifugal force is enough to overcome the pressure of the pawl 23. Winding effect takes place only at cranking speed, for when the timing lever is advanced, the pawl 23 is raised by the cam 8 to clear the dogs 12.

It will also be seen that with my improved construction, by removing the casing 21, the disk 11 and the parts coacting therewith, the drivin means for the ma neto may be attache directly to the shat 9 without any alterations being necessary.

From the foregoin description it will be readily seen that I have produced such a device as substantiall fulfils the object of the invention as set orth herein.

While this specification sets forth in detail the present and preferred construction ofthe device, still in practice. such deviations from such detail may be. resorted to as do not form a departure from the spirit of the invention, as defined by the ap pended claims.

Having thus described my invention what' ,I claim as new and useful and desire to secure by Letters Patent is i 1. In a magneto, -a secondary pole shoe, a cam disk mounted thereto and having a peripheral recess, the shoe being turnable with the timer mechanism when the'latter is positioned to give retarded or, advanced sparks, a disk mounted to the armature shaft and turnable therewith, dogs on thedisk whose outer ends are slightly lower than the normal periphery of the cam disk, an annularly flanged member turnably mounted on the hub of the last named disk having a shaft projecting therefrom adapted for connection to a driving means, a spiral spring in said flanged member, one

end being secured thereto and the other end -mined point.

2. In a magneto, a secondary pole shoe, a cam diskmounted thereto and having a pcripheral recess, the ,shoe being turnable with the timer mechanism when the latter is positioned to give retarded or advanced sparks, a disk mounted to the armature shaft and turnable therewith, dogs on the disk whose outer ends are slightly lower than the normal periphery of the cam disk,

an annularly flanged member turnablymounted on the hub of the last named disk,

such member having 'a shaft projecting driving means, a spiral spring in said flanged member, one end belng secured thereto and the other end to the hub of the last-named disk, and a spring pressed awl slidably mounted to the magneto and a apted to seat inthe cam-disk recess when the timing mechanism is in full'retarded. position and'project into the path of the dogs while in such recess; the flanged member being provided. with peripheral slots through which the dogs project, the ends 7 of the slots being adapted to abut against Y the dogs to force them against the pawl to raise the same at a predetermined point.

' Intestimon whereof I aflix my'signature in presence 0 two witnesses.

JOHN BENJAMIN BUSHNELL.

-Witnesses:

' W. EyJormsoN,

Tou BR NNAIL- therefrom adapted for connection to a i 

